Automatic telephone-exchange system.



O. KIRBY. AUTOMATIC TELEPHONEl EXCHANGE SYSTEM.

APPLICATION FILD JUNE 19. .909.

Patented Feb. 22, 1916.

3 SHEETSSHEET l.

0. KIRBY.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNI'. I9, 1909.

Patented Feb. 22, 1916.

3 SHEETS-SHEET 2.

0. KIRBY.

AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION F|LED1UN19,1909.

1,172,866. Patented Beb.22,1910.

3 SHEETSWSHEET 3.

UNITED STATES PATENT OFFICE.

OMER KIRBY, Olla"v CHICAGO, ILLINOIS, ASSIGNOR T0 AUTOMATIC ELECTRIC COMPANY,

OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

KUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Feb. 22, 1916.

Application filed June 19, 1909. Serial No. 503,109,

the called subscriber are transmitted by,

the calling subscriber.

My invention contemplates, therefore, a system in which the electrical impulses for producing the numerical switching operations are transmitted over the line circuit by mechanism at the exchange or central station, and in which devices responsive to these impulses are provided at the substations, whereby the automatic operation of the switches at the exchange or central station may be interrupted or stopped at the proper time by the calling subscriber, cach switch operating automatically until stopped at some point in the operation thereof corresponding to the digit of the called number, and each numerical switch operating automatically as soon as connection is made therewith,.so that the only act required on the part of the calling subscriber is the stopping of the switch at the proper point in its operation, but each of the different acts on the part of the calling subscriber, one for each digit of the called number, alternating with the different numerical switching operations which occur scriber a connection in accordance with the called number.

It further contemplates a system in which numerical switches, such as selectors or connectors, are so constructed that the mere selectioa of and connection with an idle switch of either kind will serve automatically to start the operation thereof, which operation will continue until interrupted by the mechanism at the calling substation, which mechanism may be of any suitable character so far as this aspect of my invention is concerned.

It further contemplates a system in which the switches have vertical motion to select groups and rotary motion to connect with a line in any selected group, the substations being provided with step-by-step switches that operate in synchronism with the vertical step-by-step operations oi all of the numerical switches, and which also operate in synchronism with the rotary step-by-step motions of the connectors or other switches for making the final connection with the called subscribers line.

It further contemplates a system in which the substations are provided with indicators, and with means at the exchange or central station for transmitting impulses for operating said indicators in synchronism with the numerical switches, such as selectors and connectors, whereby any calling subscriber may observe the progress of the call, each indicator operating once for each digit of the called number.

It further contemplates a system in which automatic trunking switches are employed, and in which the subscribers lines are free from operating grounds at the substations thereof, means being provided for preventing seizure of a trunk by the mere taking down of the receiver at the calling substation, or by the operation of the switch hook, whereby a calling subscriber cannot undesirablyv monopolize a trunk by taking down his receiver and then waiting some time before doing the other things which are necessary for making the call.

It further contemplates a system in which the called subscriber may control the connection, and may, without releasing such connection, operate an alarm signal at the exchange or central station. whereby the called subscriber may always ascertain from which substation the call came, if for any reason this becomes necessary or desirable.

My invention also contemplates certain novel features and details of construction and combinations tending to increase the general etiicieney ot' a telephone exchange system ot this particular character.

To the foregoing and other useful ends my invention consists in matters hereinafter set forth and claimed.

In the accon'ipanying drawings Figure 1 shows diagraminatically the calling subscribers substation A and a central oliice switching apparatus involving the principles of my invention. To the line of substation A there is allotted the line switch (l, which latter is controlled by the master switch I), and at E there is represented a` first selector switch.

ln vFig. there is shown diagranin'iatically a connector switch l? of improved construetion. At ll is shown a central ringer generator, while at I a common busy signaling apparatus is represented. To the line of substation there is allotted the line switch t, which is like the line switch Figs. 1 and taken together represent the central otlice switching` aifiparatus involved in establishinga connection between the subscribcrs` stations A and A. ln Fig. l is shown a central battery B having its positi\e terminal preferably grounded at (lr. The central otlice switching apparatus is ot the general type .shown in English Patent No. 2li-fllt ot 1906. but with new arrangenient and changes ofA circuits to adapt it to operate in conncctioi'i with a two-wire systeme-that is a system in which there is no ground connection at the subscribei"'s station. The line switches (l and and inastcr switch l) are modified `forms of the snitchcdisclowd in T/m ll'cwfcrn/ [17+- fM'c/ff// oiE Januar' i. 1903i. und the l Wir/iiffn /'o/.cp/rmc .auf ol' .lune (l. lil/(h. "l'bc first selector li is ol' the saine general mechanical cme-truction :is the selector switch shown in Vl inited States Letters Pat ent No. Nlfl'jl. granted March 13E. lfltlf'. to Keith, lilrichson and llriclson. while, thel connector switch l" (lig. 2) is of the general torni shown in llnited States Letters latcnt No. 5515.176. granted March 13, 1906, to Keith. Erickson and Erickson.

lfif f5 :1nd l an,` a front. and top view'. respc. tively, of the substation impulse-indicating device.

Fig. 5 is a sectional end rien ol' thc iinpulse-indicatlng device, along the litro :1m-5 of Fig. 3.

The substation A is somewhat ditl'crent from the usual automatic substation. It comprises the usuahreceiver 2, switch hook 2, induction coil 4 which is composed ci the secondary winding 5 and primary windingr (i in series with the transmitter T. )Vhcn thtswitch hook is in normal position the ringer S. in series with the condenser t), is bridged across` the line conductors 1t) and l1. Since the central ollice switches are not operated by impulses originating at the subscribcr`sI station, there is no occasion for the usual impulse springs and wheel. There is` however. provided a device for indicating the impulses to thc calling subscriber in order that the central otlice switches may be controlled and caused to operate according to the desired number. This indicating mechanism` shown in Figs. 3, -l and 5. comprises a magnet 1:2 Yt'or operating the armature and paw] 13, which in turn, when the magnet encrgizes. rotates the ratchet wheel 1l one step, so that the pointer 1,7 moves over the scale. To the ratchet wheel 1-1 there is secured the arm 1G. to which latter there is fastened one cnd of a coil spring 1T, the other end ot' which is secured to a pin. This spring 1T provides the means for restoring` the ratchet wlncl and pointer when the dog.r

1S is out ot' engagement with the teeth ot the wheel 1l. The push button 19 controls the switch hook. the springs 20, 21 and and also the dog 1S. which latter maintains` the ratchet wheel 'H- in its advanced position. rl`he switch hook is locked in its normal position by the catch 22E. as shown at 162 at substation (Fig. 2) .j but when the receiver is removed and the button 19 pressed, the catch is carried ont of its locking position and permits the switch hook to rise, \\.'hcreby tht` spring 2l is carried from the spring 25 into contact with the spring :26. Also, the arm 2T upon the rod 28 carries the spring 21 from the spring 22 into Contact with the spring 2t). thereby bridging the resista nce coil QS) (Fig. 1) across the line conductors` l() and 11. Furthermore` when the button 1f) is pressed. the member 30 engages the end of the lever 1S. moves the shaft 3l, and carries the dog out oi' contact with the ratchet teeth. ln response to the tensicn of the spring 1T the wheel t4. returns to normal` thereby restoring the pointer 15 to starting place on the scale.

clearer understanding of my improved .system may be had from an explanation of its operation when a subscriber operates the central ottico switches to establish a connection. For example, it will be pointed out how the subscriber at substation A may opcrate the main oflice switches to establish connectiox'i with the substation i (Fig. 2), the number ot' which is 220. As previously stated. in my present system there is no impulse-sending device at the subscribers sta.- tion, the impulses being made at the central office, and the subscriber controlling the number thereof by means of a push button.

When ttr receiver is removed from the switrh h lok no operation occurs; but when thtl brutta4 19 is pressed and released and the switrh hook rises the primary circuit is bridged ari oss the line conductors 10 and 11, thereby closing an energizing circuit through tht` line relay 32 of the line switch When this relay energizes a circuit is closed through the trip or plunger magnet far. hirh then operates to thrust the plunger into a bank terminal and extend the calling lire conductors to the trunk conductors leading to the tirst selector switch E. wWhen the line is extended to the selector E this switch operates automatically and independently ot' the subscriber to step the shaft and shaft wipers in a vertical direction. ly means of the button 19, however, the srhscriber controls the number of vertical impulses, and when the pointer 15 indicates L on the scale the button 19 is pressed to `bridge the resistance coil 29 across the line ionduetors, whereby the vertical steps cease and a rotary impulse occurs at the selector to rotate the shaft wipers into contact with an idle trunk line leading to a connector n itch Il (Fig. 2). The connector switch thru operates to carry its shaft wipers into Ifontact with the bank contacts corresponding to the line #220.

When the receiver is removed from the switch hook and the button 19 'is pressedy .ind released, and when the springs 24 and Z6 and 21 and 22 engage, the energizing circuit for the line relay 32 extends from ground G to the springs 34 and 35, line conductor 11, springs 24 and 26, magnet 12, transmitter 7, primary winding 6, through the springs and 21, line conductor 10 to the springs 36 and 37, line relay 32, relay springs 38 and to the battery lead 40, thence through battery B to ground G. The line relay 32, upon energizing,.presses the springs 41 and 42 into contact. As shown, the line relay is slow-acting-that is, when once energized and the energizing cir- ,cuit is then broken, the relay does not instantly return to normal position, but reu mains in its energized position fora short interval. The engagement of the springs 41 and 42 closes an energizing circuit through the trip or plunger magnet 33, which latter operates to attract the plunger arm 43 and thrust the plunger into an idle bank terminal. The plunger magnet circuit extends from ground G through the springs 41 and 42, plunger magnet 33 to the battery lead 49, thence through battery B to ground G. lVhen the plunger enters the bank terminal andolosesthe bank springs 44 and 45 in contact, an energizing circuit is established through themotor magnet relay 46, which latter operates to close the springs 47 and 48 in contact, thereby closing an energizing circuit through the motor the master switch D. The motor magnet then operates to advance all idle plungers that are in locked engagement with the plunger shaft, bringing them opposite the next idle bank terminals similar to the one just engaged. The circuit through the motor magnet relay 46 extends from ground G2 through the relay 46, common,segment 50, master switch bank wiper 49, individual segment 51, conductor 52, through the bank springs 44 and 45 to the battery lead 40, thence through battery B to ground G. The circuit through the magnet 49 extends from ground G3 to the motor magnet 49, interrupter springs 53 and 54, relay springs 47 and 48 to the battery lead 4t), thence through battery B to ground (lr.

lThe motor magnet, upon energizing, at tracts its armature 55 and the pawl 56 engages va tooth of the ratchet wheel 57 and moves the latter one step. Prior to this operation the spring 58 engages a notch of the toothed wheel 60, and when the ratchet wheel 57 is given one step the spring 58 slides from the top of the notch and engages the spring 59. The engagement of these two springs provides a new energizing circuit for ,the motor magnet 49, said cir cuit extending through the springs 58 and 59 instead of through the springs 47 and 48. Furthermore, the motor magnet when ener gized separates the interrupter springs 53 and 54, thereby breaking its own circuit in a manner similar to that of a buzzer. rI`he motor magnet 49 continues to operate in this manner as long the springs 58 and 59 remain in engagement. lVhen the next succeeding tooth on the wheel (i0 advances far enough the spring 58 disengages from the spring 59, thereby opening the energizing circuit for the motor magnet. By the time this last notch disengages the springs 58 and 59, the master switch wiper 49 has passed from the first contact point 51 to the second contact vpoint (31. Suppose, however, that when the wiper 49 engages the individual contact 61 there is a guarding potential present. ln that event an energizing circuit is closed through the motor magnet relay 46, said circuit extending from the contact 61 to the wiper 49a, common segment 5t), through the winding of the relay 46 to ground G2, as previously traced. rThe motor magnet relry again energizes and closes the circuit for the motor magnet. The motor magnet operates as before, and the wiper 49a is carried to the next contact and the next tooth ot' the wheel 60 operates the springs 58 and 59. This operation continues as long as the wiper 49 continues to find contact segments with protecting potentials. It will be understood, of course, that when the motor magnet 49 thus operates, the plunger shaft and all plungers that are in magnet 49 of locking engagement with the said shaft are moved to a new position, and thus brought opposite an idle bank terminal similar to the one engaged by the line switch C. At the instant that the plunger enters the bank terminal the following springs are pressed into contact: (32 and (S3, 6l and 65, (36 and 67. The engagement of the springs G2 and 63 extends the calling subscriber`s line conductor 10 to the trunk conductor (38, while the engagement of the springs 60 and 67 extends the line conductor 11 to the trunk conductor 69. These conductors 68 and G9 lead to the side switch wipers 70 and 71 of the first selector ll. When the line conductors 1() and 11 are thus extended to the first selector E an energizing circuit is established through the line relays 72 and 73 and private magnet relay S1. The relay 72, upon energizing. closes the springs 7l and 75 in contact, and the relay 73. upon energizing, carries the spring 76 out of contact with thel spring 77 and into contact with the spring 78. The energizing circuit for the line re'- lays 72 and 73 and private magnet relay l e,xtends from ground G4 to the relay 73, side switch wiper 71. trunk conductor 69, bank springs G7 and 6G, line conductor 11. thence through the substation A to the line conductor 10, as previously explained. bank springs G2 and 63, trunk conductors 68, side switch wiper 70, line relay 72, springs 79 and 80. through the winding of the private magnet relay 81 to the battery lead 4l), thence through battery B to ground G. The relay 81 thereupon energizes and separates the springs 87 and 88. The engagement of the springs 76 and 78 provides an energizing circuit for the bridge-cut-otl1 relay S2 in series with the plunger magnet of the line switch C. This circuit extends from ground to the side switch wiper 83. springs To and 78, conductor 84, bank springs (35 and 6l, bridge-cut-off relay 82, plunger magnet 33 to the battery lead 40, thence through battery B to ground G. The bridge-eutotf relay 82, upon energizing, would operate to disengage the springs 3o and 37, 3l and 35, thereby disconnecting the subscribers line conductors from the line switch C, had not the armature 43 already done so. The trip or plunger magnet 33, this circuit, retains the pl'unger arm 43 in au attracted position, and the plunger in the bank terminal. Thus it will be seen that tnc line switch (i, after being operated from the subscribers station` is maintained in its operated position by aground connection at the first selector E.

The foregoing is the condition of the central ofiice switches after the calling subscriber removes his receiver from the switch hook, presses and releases the button 19, and before the selector switch E operates for the vertical impulses. When the relay 72 eneralso being included in4 gizes and closes the springs 74 and 75 in contact, an energizing circuit is established through the vertical magnet 85 and the slow-acting relay SG in multiple. This circuit extends from ground G5 through the side switch wiper 83, springs 7G and 78, springs and 71, springs 89 and 90, through the vertical magnet 85 and slowacting relay in multiple to the battery lead 40, thence through battery B to ground G. The vertical magnet S5 thereupon energizes and operates to raise the shaft wipers 91a., 92a and 93 one step in a vertical direction. The slow-acting relay S6, upon energizing, carries the spring 80 out of engagement with the spring 79 and into contact with the spring 91. lhen the springs 79 and 8O disengage, the energizing circuit through the line relay 72 and the magnet 12 in series becomes broken, and the relay 72 restores to normal, permitting the springs 7l and 75 to disengage. Vhen the springs 80 and 91 engage., a new energizing circuit is established through the line relay 73, said circuit extending from ground G" through the relay 73, conductor 92, through the springs 91 and 80, private magnet relay 81 to the battery lead 40, thence through battery B to ground G. The relays 73 and 31, therefore. remain in their energized position. when the relays 72 and 73 energize, the magnet 12 at the substation A also energizes. thereby attracting its armature 13 and moving the ratchet wheel 14 one step, carrying the pointer 15 to the scale division marked 1. Vhen the relay 72 deiinergizes, the springs 771 and 75 disengage; also, the magnet 12, being deprived of its energizing circuit. restores to normal position. The disengagement of the springs 7l and 75 of the line relay 72 breaks the energizing circuit for the vertical magnet 35 and the slowacting relay S6. The relay SG, therefore, returns to normal position, whereby the spring 80 again engages the spring 79, and the energizing circuit for the line relay 72, in seriesY with the ma net 12 and the line relay 73, is again esta "ilished, The relay 72, therefore, energizes and presses the springs 74 and 75 into contact, whereby the circuit through the vertical magnet and the slow-acting relay 8G is again established. The magnet S5 operates the switch shaft one more step. and the relay 86 breaks the circuit for the line relay 72 as before. The magnet 12 also operates the second time and the pointer 15 is moved over the scali` to the division marked 2. This indicates to the calling subscriber that the selector s itch has traveled two vertical steps, and that the shaft wipers 91, 92a and 93 have been raised to the second level, opposite the trunk line conductors which lead to the connector switch F. It

1t should also be explained that.

. circuit for the said private should be stated that if necessary the relay 72 may be made slow-acting to any suitable degree. The subscriber at substation A then presses the button 19, whereby the spring 21 is carried out of engagement with the spring 22 and kinto enga gement with the spring 20. This operation breaks the circuit through the magnet 12 and bridges the resistance coil 29 across the line conductors 10 and 11. Vhen this resistance enters the circuit in series with the line relays 72 and 73 and the private magnet relay 81, sufficient current does not How to maintain the relay 81 in its operated position. It therefore restores to normal and the springs 87 and 88 engage, whereby a circuit is closed through the private magnet 94. This circuit extends from ground Gf through the side switch wiper 83, springs 88 and 87, conductor 95, through the winding of the private magnet 94, normal springs 9G, 97 and 98, through the winding of the release magnet 99 to the battery lead 40, thence through battery B to ground G. The private magnet 94 has a sufficiently high resistance to prevent enough current from flowing over this circuit to operate the release magnet 99. The depression of the button 19 also disengages thedogv 18 from the ratchet wheel 14, thereby allowing the indicator 15 to be restored to normal position in the manner explained in connection with Figs. 3, 4 and 5. v

When the button 19 is restored to normal position suihcient current again flows to energize the relay 81, which thereupon operates to disengage the springs 87 and 88, whereby the energizing circuit for the private magnet 94 is broken. The private magnet, upon energizing, operates the sprin'gs 89 and 90, so that when the relay 72 energizes afteigthe button is pressed an impulse will not be transmitted to the vertical magnet 85. The private magnet, as is well known, upon energizing and de energizing, permits the side switch to pass from tirs-t to second position, whereby when the wiper 100 engages the .contact point 101 an energizing circuit is established through the rotary magnet 102. The rotary magnet then operates,to rotate the shaft wipers 91, 92H1 and 93 of the selector' E into engagement with the first Contact of the second level of the selector' banks, from which contacts it is assumed the trunk line conductors 10?, 104 and 105 lead to the connector switch lP (Fig. 2). If the first trunk line is busy, however, and the wipers have to pass over busy contacts, then as soon as the private wiper 93 engages the first private bank contact and the private magnet 91 is again energized and the .side switch is locked in second position. The energizing magnet extends from the grounded terminal G of the battery B through an occupying switch (not shown), through the private wiper 93, side switch wiper 10G, contact point 107, then i through the private magnet 94 and normal springs 96, 97 and 9S, release magnet 99 to the battery lead 40, thence through battery B to ground G. The private magnet 94, upon thus becoming energized, locks the side switch wiper 100 in engagement with the contact point 101, whereby the rotary magnet 102 will be energized step by step until the wipers are carried beyond the last busy trunk line. At the instant that the private wiper tact point the energizing circuit through the private magnet 94 is destroyed, and as a result the selector side switch passes to third position. If there are no busy trunklines the rotary magnet 102 releases the side switch to third position as soon as the wipers are carried into engagement with the iirst trunk line. As soon as the side switch passes to third position, as stated, the subscribers line conductors 10 and 11 are eX- tended to the trunk conductors 103 and 104 which, in this case, it is assumed lead to the connector switch F. The extending of the line occurs, of course, as soon as the side switch wipers and 71 engage points 108 and 109, respectively. Also, when the side switch wiper 106 engages the thirdposition contact point the guarding potential is established at the private bank contact corresponding to the trunk line conductors 103 and 104 for protecting the said trunk line against interference by another calling subscriber. The wipers of the side switch are broad enough to bridge across the space between the contacts, so that the battery is not disconnected from the line while the side switch is moving from one position to the other. When the subscribers lineI conductors are thus extended to the connector switch F an energizing circuit is established through the line relays 110 and 111 and private magnet relay 118 in the same manner in which 'the energizing circuit was established through the line relays 72 and 73 and private magnet relay 81 of the selector switch E when the subscribers linc conductors 10 and 11 were extended to the trunk conductors (i8 and 09 through the line switch bank. The circuit through the line relays 110 and 111 and private magnet relay 118 extends from ground G through the relay 111, trunk conductor 104, shaft wiper 92, side switch wiper 71, truuk conductor G9, thence through the substation A to the trunk conductor 08, as previously traced` side switch wiper 70, shaft wiper 91. trunk conductor-'103, line relay 110, @p1-imag 116 and 117, through the winding of the private magnet rela)r 118 to the bai.- tery lead 40. thence through battery B to ground (l. The relay 110, upon energizing,

93 leaves the last busy con? the contact closes the springs 112 and 113 in Contact; the relay 111, upon energizing, separates the springs 114 and 115, and the private magnet relay 118, when energized, separates the springs 119 and'120.

The engagement of the springs 112 and 113 provides an energizing circuit for the vertical magnet 121 and the slow-acting relay 122 in multiple. This circuit extends from ground (i7 to the springs 112 and 113, springs 123 and 1.24, side switch wiper 125, thence through the vertical magnet 121 in multiple with the relay 122 and the rotary magnet 1213 in series to the battery lead 40, thence through battery B to ground G. The vertical magnet thereupon energizes and operates the switch shaft to carry the switch shaft wipers 127, 12S and 129 one step in a vertical direction. 1t should be stated that if necessary the relay 1,10 may be made. slowacting to any suitable degree. Although the rotary magnet 126 is included in the circuit with the slow-acting relay 122 it does not operatively energize. since the said magnet is of comparatively low resistance. rl`he relay 122, however, energizes to separate the spring 117 from the spring 11G and carries the spring 117 into engagen'ufnt with the spring 127, 'hen the springs 116 and 117 disengage, the energizing circuit for the line relay 110 and the magnet 12 at the station A is broken. The relay 11() and the magnet 12 therefore restore to normal position. Vb-en the springs 117 and 127 engage, a -new energizing circuit is provided for the line relay 111, said circuit extending from ground (1 through the relay 111, springs 127 and 117, private magnet relay 118 to the battery lead 49. thence through battery li to ground G. 'lhe disengagement of the springs 112 and 1131. when the relay 110 restores to normal. breaks the energizing circuit for the vertical magnet 121 and the slow-acting relay 122. After a moment the slow-acting relay 122 restores the spring 117 to normal engagement with the spring 116,

lwhereby the circuit provided for the line relay 110 in series with the magnet 12 of the substation A and the lil e relay 111, together with the private magnet relay 11S. The line relay 110 again energizes and places the springs 112 and 113 in contact whereby a Second energizing circuit is established `through the vertical magnet 121 and the slow-acting relay 122, as before explained. rThe vertical magnet operates as before, and the shaft wipers 127, 129 and 129 are raised a second step and brought opposite the second bank level. The substation magnet 12, upon energizing the second time, moves the pointer 15 opposite the number 2 on the scale, thereby indicatingr to the subscriber that the connector switch has operated for the seeond digit 2 of the desired number.

As shown in the drawings, the magnet 12 .his button before the at the substation will be energized and the pointer moved one step as soon as the button 19 is released after the first digit is called. 1n case the wipers of the selector E have to rotate over several busy trunks, this move ment of the indicator would take place a short time before the vertical magnet of the connector F is energized, and if the digit to be called were 1 the subscriber might press connector has time to operate. This would not result if any other digit than 1 were called. because the magnet 12 at the substation would not be energized a second time until the shaft of the connector had actually been stepped up two steps. It will thus be understood that the possibility of the subscriber pressing his nntwhat amounts to the same thing, if tia` raancs arr so arranged that it requires two cal steps of the shaft to raise the Xliptjs to a position opposite the first bani. ievel. ln sur-h case there would be no subsmihers munbers whose tens digit is 1. and consequently there would be no danger of the calling subscriber pressing his button before the connector has operated the number of times indicated by the pointer.

After the pointer reaches the No. 2 position on the scale the button 19 again pressed to stop the vertical impulses and to step the side switch from first to Second position. vWhen the button 19 is pressed the .springs 21 and 20 engage, thereby bridging the resistancecoil 29 across the line conductors 1() and 11. The relay 110 again energizes when the slow-acting relay 122 restores to normal position with the spring 117 in contact with the spring 116, but with the resistance coil 29 bridged across the line conductors 10 and 11 in series with the line relays 1l() and 111 and the private magnet relay 118 suitici'ent current does not flow to maintain the relay 118 in its operated position. The springs 119 and 120 therefore engage and close an energizing circuit through the private magnet 130 in multiple With the slow-acting relay 131. This circuit extends from ground (is through the springs 119 and 120, normal springs 132 and 133, side switch wiper 134, contact point 135, slowacting relay 131 in multiple with the private magnet 130 to the battery lead 40, thence through battery B to ground (i. The relay 131, upon energizing, separates the springs 123 and 124.

lhen the button 19 restores to normal the resistance coil 29 is eut out of the line circuit. and permits sufficient current to flow so that the relay 118 again energizes and breaks the energizing circuit for the private magnet 130. The private magnet, upon energizing and delle gizinf, permits last.

called subscriber removes the receiver from the switch hook and presses and releases the button 161. lhen the button 161 is pressed the lock 162 is carried out of engagement with the switch hook 163, and the switch hook rises, carrying the springs 158 and 164 into contact, thereby closing the primary circuit for the substation A. The transmitter 165 of the substation A is provided with battery current from ground G" through the relay 166, through the ringer relay springs and side switch wiper to the normal conductor 138. line conductor 159, springs 138 and 164, through the magnet 167. transmitter 165, primary Winding 168. springs 169 and 170 to the line conductor 154, normal conductor 137, through the shaft and side switch wipers, ringer relay springs and relay 171 to the battery lead 40, thence through battery B to ground G. The transmitter 7 of the calling substation A is provided with talking current through the line relays` 110 and 111,'and private magnet relay 118 as previously traced. The two substations being thus connected, conversation may be carried on over the conductors indicated by the heavy lines in Figs. 1 and 2.

The release of the central otlice switching apparatus is brought about by the subscriber who restores his receiver to the switch hook Suppose. for example, that the subscriber at substation A has restored his receiver; then the relays 171 and 166 restore to normal position, placing the springs 148 and 149 in contact. The release of the switches is then`brought about when the subscriber at substation A restores his receiver to the switch h'ook. Vhen this occurs the springs 24 and 26 disengage, thereby breaking the energizing circuit which includes the line relays 110` 111 and private magnet re lay 118 of the connector switch F. When the switch hook 3 reaches its lowermost position the locking member 23 passes over the top of the switch hook 3, as shown in Fig. 2, and locks the switch hook in its downward position. Also, when the switch hook is moved about its pivot point 172 the rod173 rotates the shaft 31 and carries the dog 18 out of engagement with the ratchet Wheel 14. lVhen the springs 24 and 26 disengage and break the energizing circuit for the line relays 110, 111, an private magnet relay 118, as explained, the said relays restore to normal position, whereby the springs 114 and 115 now engage and close an energizing circuit through the release magnet 140i of the connector F in series with the release relay 173 of the selector switch E. This circuit extends from ground G10 through the release relay 173, side switch wiper 106, shaft wiper 93, conductor 105, springs 115 and 114. through the normal springs 175 and 176. release magnet 140% springs 148 and 149 to the battery lead 40, thence through switch hook first, then the circuit for battery B to ground G. The release magnet 140 attracts its armature and restores the connector side switch to first position, and the connector switch .shaft and wipers 127, 128 and 129 are restored to normal. 70 When the shaft reaches its normal position the normal arm 177 upon the shaft carries the springs 176 and 133 out of engagement with the springs 175 and 132. `he disengagement of the springs 175 and 176 breaks 7 the energizing circuit for the release magnet 140, The release relay 1.73a of the selector switch E also energizes in series with the release magnet 1402t and operates to Aclose the springs 178 and 179 in contact, thereby closing an energizing circuit through the release magnet 99, said circuit extending from ground G to the springs 178 and 179, release magnet 99 to the battery lead 40, thence through battery B to ground G. The release magnet 99 thereupon energizes, restoring the selector side switch and shaft wipers to normal position, lVhen the shaft reaches normal position the normal arm 180 upon its end disengages the springs 96, 97 and 98. lVhen the selector side switch re stores to normal position the holding circuit through the bridge-cut-ofi' relay 82 and plunger magnet 33 is broken. It will be seen that after the selector side switch 95 passes to third position the holding circuit for the plunger magnet 33 extends from ground to the side switch wiper 100, contact point 181, conductor 84, bank springs 65 and 64, bridge--cut-off relay 82, plunger magnet 33 to the battery lead 40, thence through battery B to ground G. Now, when the side switch wiper' 100 restores to normal position this circuit is broken and the relay 82 and release magnet 33 denergize, whereby the arm 43 restores to normal position, permitting the springs of the bank terminal to restore to normal position. The calling subscriberthus, upon hanging his receiver 2 upon the switch hook 3.r opens the primary circuit at the springs 24 and 26, whereby the line relay 111 of the connector' switch F is denergized. bringing about the release of the central oflice switching apparatus, as explained. If the calling subscriber should restore his receiver to the the release magnet .140L is closed in a somewhat different manner. AIt Was explained that when a calling subscriber restores his rc- 120 ceiver to the switch hook the line relay 111 denergizes and permits the springs 114 and 115 to engage; buta if the called subscriber at station A still has his receiver off the switch hook. thus maintaining the energiz- 125 ing circuit for the relays 166 and 171, the circuit for the release magnet 140l is not closed. When the receiver at substation A is restored, the relay 171 denergizes, permitting` the springs 148 and 149 to engage, 30

whereby the energizing circuit for the release magnet 14()a is now completed. The release magnet energizes in series with the back-release relay ot' the selector switch E and produces the release of the central oiiice switching apparatus, as previously7 eX- plained.

1n the foregoing it has been pointed out how a subscriber might operate the central otlice switches to establish connection with another subscribers line. Suppose, for example. that when the subscriber at substation A calls the subscriber at station A the line is busy-that is, another subscriber had called station A, or the subscriber at substation had made a call to some other station. 1n either event a guarding potential will be established at the private bank contact in the connector bank corresponding to the line ot' substation A. Then. after the connector switch l*` is operated for the last digit 0, and the push button 19 is pressed to step theI connector side switch Lwipers from second to third position. an energizing circuit is established through the private magnet 130 and relay 131. and the sidel switch is locked in second position. rThis is brought about as follows: 'hen the button 19 is pressed the private magnet 1211) energizes as before, and closes the springs 1262 and 18S and 181 and 1ST) in contact. \\'hen the springs 16,2 and 1S?) engage. a locking circuit is established for the private magnet 13() and relay 131, said circuit extending from the grounded private bank contact to the shaftl wi rr 12S). conductor 140, side switch wiper 130, contact point 186 (bearing in mind that the side switch is now in second position) to the springs 162 and 183, private magnet 13() in multiple with the relay 1231 to the battery lead 40. thence through battery B to ground The pri vate magnet and relay 131 are thus enen gized and the side switch is locked in second position, and the subsrriber`s4 line is not extended to the normal conductors of the desired line. The busy signal. however. is given the calling subscriber. "ndicating this condition. The busy signal current passes from the secondary winding of the busy machine l to the springs 185 and 184', condenser 145, trunk conductors 10i and 69, line conductor 11, through the substation A to the line conductor 10, trunk conductors 68 and 103, .through the relay 110, springs 116 and 117. private magnet relay 118 to the battery lead 40, thence to the secondary winding again. The calling subscriber is thus notified thatvthe desired line is now in use and. upon hanging up the receiver, brings about the release of the switches in the usual manner.

ln regard to the action of the relay 86, it may be added that the springs are so adjusted that when the relay is energized the spring 80 makes contact with the'spring 91 before leaving the spring 79. Otherwise the circuit through the relays 73 and 81 would be momentarily broken each time the vcrtical magnet and the relay 86 are energized. The magnets and relays in the system may be adjusted to any suitable degree, and may be made slow or fast to any suitable extent if desired.

Means are also proy ided at each connector whereby the, called subscriber can signal the. exchange attendant. in case a` connector is in connection with the line for a long time, or in case the subscriber is being annoyed by other subscribers. This is accomplished by the relays 166 and 171 in connection with the button 161. When the button 161 is pressed the high resistance is inserted in the line circuit. whereby sufficient current does not flow to hold the relay 166 in an operated position. 1t accordingly' falls back and cuts battery to an alarm or other device such as the lamp 106. which will attract the attention of the attendant to this connector.

From the foregoing it will be seen that I provide a system in which automatic trunle ing and connecting operations are accomplished without they provision of any means for transmitting impulses over the lines from the, substations thereof. To the contrary the makc-and-break devices for transmit/'ng the electrical impulses are located at he exchange, or central station, and while, these impulses are being transmitted over the line circuit. the latter remains closed at tbe substation thereof. the said substation being provided with devices for merely checking or stopping the transmission oi impulses as soon as the automatic switch that is operating in response thereto has reached a desired or l'nedeteru'iii:ed point in its operation. which predetermined point always corresponds to a` digit oi? the falled number. 1n this way a selector always stops at a level corresponding to a digit of the called number. and then rotates automatically to find an idle trunk in the predetermined group. A connector, howevei, as herein disclosed. is not only stopped at a predetermined point in its vertical operation, so as to select a predetermined group of subscribers, but is also stopped at a. predetermined point in its rotary operation, whereby connection is made with the called line. During the vertical operation of a selector the calling subscriber is doing nothing, as at such time the system is operating automatically. and is not under the control of the calling subscriber. This is also true when a connector is operating vertically. and is true while the connector is operating in a rotary manner to find the called line. lill ol' the :iets of the calling subsrrher Ire merely :for the purpose of stopping? inw willi-'na at the predetermined or (leairefl point4 in their operation, and :ire no( lo: the purpose of musing the switches to operate, with the exreption, ol course, of the initial act ol' the subscriber which causes the liney ,witeh to opemte. The nunierieal switehea. lo-wity. the selectors and connectors, are'earh adapted to automatically respond as' soon as ronneetion is n'mde therewiththat is to Say, the mere seizure ol the itlle trimli line Causes the selector or connector aty the other end thereof to begin to operate. and 'its operation. continues until .Stopped or inlerrupll-ll h v reawn of some positive actk on the part or' the Falling Hulwcrilier, am! not, iwranee the wallingr snlsrrilwr has mwN-l to ley .something- 'l`he indicator at he 'allingr @uhstation is responaiw to the wrti'ra" 'pen-tion of the aelrrtorr. int not to lla rotary operations {herr-ffl", The saill .mliralor i. howewrt reep we 12 lioth the wrliral am! rotary,r ,:peraionra el: the connerlor. as; preriomljv rxplainffii, 'llllm the inilivaUr at the willing enlistation rremznls anrl operates ln ,lw'relnonisin with all ot the nnnn-rieal switching: operations at the exrhange or venral station. The Falling4 Sul)- ,wrilwr :slope the inelivator and the Aawiteh llaa ik: aieralwf' in sin. l-ronifnn therewith :il fn llixfreof rorreago-1 mi o 1w f@ eine calmi number. Home the ai lln: snheerilwr Vhiuh l-tops th ,}.=-r.tl.ion at, the required moment la ze lolnierl alter the requisite degree, ot' oz'mraion im taken place, and the toppag1e nl the writrhing operation occurs` aisnnltanefinely Milli the am of the anlmf'imer. For Lhelnlofnler pnrpowe; ofmy invention, how- M'er, the met el the finllgcriher which tops the switch at the flesirecl point in it v operation malv orfm' either l' ol' :xl'tyt r the saifl operation fw: :liarlfwexh the arlS nl' the tzal-arriba' aliernale with llie sin :;i^ra\iriz; or :lu wifflies. :intl 'Linn Hilfs o? whether the :lift oliA the wing: lla operation ol the lllfr-,lrwthal olnwalion, wl that li) in): inw-intiem l 1ffzhirn raul-fire svaiii'ir limi, is lo l? on@ auf my Stom -igneinxing' .if wiwi, al the mlmations thereof En .-flm li the -nlm ller-s' lima@ 'ire prornlrrl with non invii mm'ierral trnnli'infg awitrhen and in whirh provm'on in made whereby the taking (loan of the revolver at the milling; ennemi/nin flow; not rmsnlt in the 'e of a 1Min-lf or tru line :il the central Station. la: lli` wa); and notwithfstsmling that the will law: are rontrollerl over complete melallifline riz-unile" the calling siiliftzriber emmot take llown hiey receiver and 1monopolize a trank line for some time before completing the call. With the fallingr sulle my improved arrangement no trunk line is seized until after the callingr Subscriber has pushed the button and thereby starte/l the operation of the .fwrm to exleinl the eal toward the eallell Subscriber. ln addition it will he seen that provision made for enabling` a called snbseriher to Sig-nal an attendant at the exeliange or ventral ,station without llisronnerling his line l'rom the line of the railingn enlmrilier. ln this way the eallell Subscriber 'van always ascertain from where the Call farne-that is to say, van always meertain the nnmher ot' the ailing snhsrriher. This is ol advantage for rarioli reaaons, as, for example`r in cases where one snlserilwr annoys another hy persistently calling him sap fr no other reawn. ln sm'h rase, :xml will) my imprmml arrangenwnt, the mlm'rilwr thus annorwl may signal the alfemlant :il the x1-hangt or central Station without reh @mi the Comun; lion. 'lha' aid asenrn wnznmnieating with ihr #allor im; ran then traer tlnA all had .Ilm-nel; the exrliangfe to 11:1A :mi: i from winnfne n rameL 'illus :my rallwfl :alliserihel alrv:r\' hal ii within hi I power 'to retain the ron neetion :unl thrrvlrr awerlain from whenre the fall (farne. railing' ronnerion ways released ltr ilaz enliarrilwr who hai up his receiver last.

lvlnil l Claim my invention is: Y'

l. in a twwwirv or nn-tallir wirenl-ron Lrollell triinllngl .4jstern.lrnnklinesnz `ewilrl; for seleuting a trol-ik. :nerim at the enlist-:l ion separate from the ,@wtrla hook normally tending lf3. winlrol kl ,ewiirh to rana il to seine a rnnlflw 1hr inilialrloane ol' a melallil; viren-it iw :z walling snlierrilier. :znfl meany lor prl-wniinr this operation,

Joliet www. lilimlu. lill iwi, lim;

minimaal will i Il* or llnf'a l. ln a motion in e, tunning a erm nlmlviimy-` mn' li nilmlien to exteza Called mln-'riber.

l operation al F-,tzilmrn nun xiii Sipra rligjil, ol thi* (viii-l `g ronn'ertion toward the i. whetalion mef'haniam ai von rfiionive to each lllll means at the substations by switching operation, operating in synchronism therewith, and means the initial operation of which variably limits the operation of said mechanism, whereby the calling party controls the extent of said operations.

4. In a telephone system, means for performing a series of numerical switching operations, one for each digit of the called number, to extend connection toward the called subscriber, a visual indicator operating in synchronism with each of said operations, and mechanism the initial operation of which stops said indicator at any point in its operation, whereby the calling party may observe and control the said switching operations.

5. In a telephone system, a series ot' switches, means for automatically operating said switches to extend connection toward the called subscriber, and a mechanism by the initial operation of which the calling party terminates the operation of each switch in Iaccordance with a digit of the called number, said mechanism being at rest during the actual operation of any switching party alternating with the operations of said switches.

6. In a telephone system, an automatic two-motion switch, a metallic line circuit therefor, meanS atmthe switch for opening` and closing said metallic line circuit to cause a step-bystep operation of said switch, and means by which the calling party controls the extent of operation of said switch after said switch h-as started in operation.

7. In a telephone trunking s vstem` a metallic line circuit, an automatic switch .having vertical step-by-step motion to select a group land rotary motion to find an idle trunk in the predetermined group, and auto! matic neans at said switch for controlling the two sides of said line circuit to cause the said' vertical motion.

8. In a telephone system, a line circuit. au automatic switch having vertical step-bystep motion to select a group and rotary I.motion to find the c'alleol linen in the predetermined group, and automatic means at said switch for controlling .the two sides of the line circuit in series to cause the said vertical and rotary motion.

9. 1n a telephone system. subscribers metallic line circuits, automatic switches, devices at the exchange or central station for ,automatically controlling said metallic line circuits? to cause the operation of said switches, indicating meansat the substations responsive to cach switching operation, and

which the subscribers control the extent of operation of said switches in accordance with the digits of called numbers.

10. In a telephone trunking system, trunk lines divided into groups, means for autothe connection controllable only by matically selecting groups and means for selecting an idle trunk in a predetermined group, a line circuit automatically controlled at the exchange or central station to cause the group-selecting operation, and means by which the calling party controls the line circuit to terminate said operation in accordance with a digit of the called number after said switch has started in operation.

11. ln a telephone system, means controllable by the calling subscriber over two sides of the line in series for automatically extending connection from the calling line to the called line. and means for releasing the subscriber who hangs up his receiver last.

12. ln a telephone system, automatic means controllable by the calling subscriber for finding and extending connection to the line of the called subscriber` means for releasing controllable only by the subscriber who hangs uphis receiver last` a central station signal responsive only to the called subscriber. and means for preventing a release of the connection when the called subscriber operates the said signal.

13. ln a system for establishing complete metallic talking circuits between calling and called subscribers. a line circuit, means for performing a series of numerical switching operations. one for each digit of the called number. to extend connection toward the called subscriber. devices at the exchange or central station fer transmitting impulses over the linecircuit to operate said means, and a controller mechanism by which the calling party li'mits tbe said impulses in accordance with the digits of the called number. said mechanism being at rest while the impulses are being transmitted over the line. aand the acts `of the calling party for limiting said impulses alternating with the numerical switching operationsat, the exchange or central station. said system being controllable over the two sides of the subscribers line in series.

14. In a system for establishing complete metallic talking circuits between calling and called subscribers. means for performing a series of numerical switching operations one for each digit of the called number. to extend connection toward the called subscriber. a substation mechanism responsive to each switching operation, operating in synchronism therewith, and means for variably limiting the operation of said mechanism, whereby the calling party controls the extent of said operations, said system being controllable over the two sides of the subscribers line in series.

15. ln a system for establishing complete metallic talking circuits between calling and called subscribers, means for performing a Series of numerical Switching operations, one for each digit of the called number, to extend connection toward the called sub acriber, a visual indicator operating in Synchroniffm with each ot' Said operations, and mechanism for stopping said indicator at any point in its operatimi. whereby the eall ing party mayY observe and control the said Switching! operations. said System being controllable over the two sides of the Subscribers line in series.

lll. ln a system for establishing complete metallic talking circuits between calling?- and called subscribers. a Ferien ot' Vqwitches. means for auton'iatieally operatingm Said switches to extend connection toward the called vSubscriber. and a nieclninism by which the callin;r party terminates the operation ot' each awitch in accordance. with a digit of the called number. Said mechaniSn'i being: at resti during' the actual operation olt any switch. the actuation ot Said nieclianism by the callin;T party alteri'iating with the operations ot Said switches. Said system being" controllable oyer the two @iden of the Subvscribers lineI in Serien.

17. ln a SyStcm for establiahing complete metallic talking circuits between calling and called subscribers, an automatic Switch. a line circuit therefor.y means atithe Switch for opening and closingthe line circuit to cause a Ste}' -byStep imei-ation of Said switch, and means by which the callingr party controls* the extent ol operation ot' said switch, Said syntem bein;d controllable oyer the two Sides of the .Qul'iocribens line in Qeriea.

1H. ln a system l'or establishingr complete. metallic talkiim circuits between callingand called subacribera. a line circuit. an antomatie, awitcli baring yertical ateirbyvatep motion to select a group and rotary motion to lind an idle Trunk in the predetcrniined group. and aanmnatic lucana at Said switch tor controlling` the line circuit to cause the Said Vertical motion. .will @3ft-ni licingf conH irollalile over thc tac -iil ol llic, ulie1crib er1; line in serien.

lil. ln a sy tem lor caiabliabing complete metallic talking..r circuihy between callingr and called ub cribcr a line circuit. an antomatic switch lening vertical stcp-by-f tep motion to select a group and notary motion to find the called line in the ]u'edetcriniiwd group. and automatic mear` at said lwitch For controllingr the line circuit to cauee the said `wai-tical and rotary mulion` Said system bein;r controllable over the two sides` ot the ubscriberav line in Serien.

20. ln a iSwtem tor eslaldiallingY complete metallic talking' circuits between calling and called subscriberx. sulmribers line circuits, automatic switches` dcyiceS at the exchange or central Station for automatically controlling said line circuits t0 cause the operation of Said switches, and means at the substations by which the subscribers control the extent of operation of said switches in accordancel with the digits of called numbers, said syS- tem beinglr controllable over the two sides of the .#:ulcriber.` line in series.

2l. In a system for establishing complete metallic talkingr circuits between calling and called subscribers, trunk lines divided into groups, means for automatically selecting a group and for aeleet'inge,` an idle trunk in a predetern'iined group. a line circuit automatically controlled at the exchange or een tral station to cause the, group-selecting operation. and means by which the calling party controls the line circuit to terminate said operation in accordance with a digit of the called number. :said system being' controllable over the two sides ot the Subscribers linl in Series.

ln a system ot' telephonie transmis-- sion between calling' and called subscribe a line circuit. meam-l tor pertorming a Series ot' numerical switching' operations. one tor each digit. of the called number. to extend connection toward the called subscriber, deyiceJ` ai the exchange or central station for transmitting impulses over the line circuit to ope ate said ineanx a controller mechanism by which the. callingr party limitl the .Quid impulses in accordance with the digiti ot' the called number. said mechanism being at rest while. the impulses are hein;f transniitted over the line. and the acts oi' the callingY party for limiting: aaid impulses al ternatinl;r with the numericzl switching; op erations4 at the exchange or central station5 and `aubstation transmitters connected to receiye talking current trom the exchange or central ,station QS. ln a .System ot' teleplu'inic tran'amis lon between callingr and called SulScrilfer.-. neanf for performing a series ot' numerii :il ,wf-'itching` operationa. one l'or each digit ot thc called number5 to extend connection toward the called aubeeribcr. a eulmtation mechanism reeponsiye lo each switching op eration` operatinflr in :ayucliri'inism therewith meain` controlled by the calling sulmerilai' l'or iariably limiting said ewitching invern-- tion. whcrehr the callinffparty controla tlle e\tenl ot' said operations. and subatation tranamitter` connected to receive talkingr current trom the exchange or central Station.

il. ln a aystem ot telepln'mic transmission between callin;r and called Subscribers. means tor performing; a Series; of numerical :switching` opel-aliena. one for each digit o1" the called number` to extend connet 'in toward the called Subscriber, a visual indicator operating in synchronism with each of said o]' e rations mechanism for Stopping said indicator at any point in its operation,

il O

lili

whereby the calling party may observe and control the said switching operations, an

substation transmitters connected to receive talking current from the exchange or centra station.

23. ln a system oi' telephonie transmission bet wecn calling and called subscribers, a series ot' switches, means for automatically operating r iid switches to extend connection toward the called subscriber, a mechanism by which the calling party terminates the operation of each switch in accordance with a digit of the called number, said mechanism being at rest during the actual operation of any switch. the actuation of said mechanism by the calling party alternating with the operations of said switches, and substation transmitters connected to receive talking current from the exchange or central station.

G. ln a system ot telephonie transmission hetweei'i calling and called subscribers, a line circuit, an automatic switch having vertical stepdiy step i'notion to select a group and rotary moi-,ion to lind an idle trunk in the pre deiei niiued group. automatic means at said .viti'li l'oi cont rolling the line circuit to raie-ie the said wrtical motion, and substaiioii transmitters connected to receive talking current from the exchange or central st tion.

i. la .i erstem of telephonie transmission betr. een calling and called subscribers, a line circuit, an automatic switch having vertical stri` by-step motion to select a group and rotary motion to tind the called line in the predeteruina-d group, automatic means at said switch for controlling the line circuit to cause the said vertical and rotary motion, and substation transmitters connected to receive talking current from the exchange or cent ral station.

ln a system of telephonie transmission between calling and called subscribers, sub- ,-11 ribers" line circuits, automatic switches,

duif-es al the exchange or central station l'or :oiioinatically controlling the two sides oi' said line circuits iii series to cause the operation olf said switches, means at the substa ioi..`1 'oy which the subscribers control the extent oi operation of said switches in accordance with the digits of called numbers, and substation transmitters connected to receive talking current. from the exchange or central ystation.

Lil. lii a svslriu ol' telephonie transmission between raltng and ralled :s'iibsrribei-s, trunk lines diiidrd into groups. uieans l'or aulo liialiially .selecting a group and tor si lerting an idleI truuk iii a predeteruiineil group, a line fil-ruit, aiili-iiiiitirriily controlled :it the :inge or cridral station to cause the selecting' operation, means by which paity controls the linel circuit lo arrordance with rrr.

ji-ii lliv calling' terminate said operation in a digit of the called number, and substation transmitters connected to receive talking current from the exchange or central station.

30. ln a telephone system, an automatic selector switch provided with a plurality of relays, the first and second of said relays being normally in bridge of the line circuit, a circuit including the winding of the first relay in series wziththe winding of the third relay, means whereby the first and fourth relays cooperate to transmit electrical imulses over the line circuit, a magnet at the substation, indicating means operated by said magnet in response to said impulses, release mechanism for said selector, means for releasing said switch, and a resistance at the substation for preventing premature operation of said release mechanism. A

3l. In a telephone system, an automatic connector switch provided with means for finding the called subscribers line, a plurality of relays for said connector, the first and second ot said relays being bridged across conductors of the talking circuit, a circuit including the winding of the first relay in series with a winding of the third relay, means whereby the first and fourth of said relays cooperate to transmit electrical impulses over the line circuit, a magnet at the substation, indicating means operated by said magnet, in response to said impulses, release mechanism for said connector, means for releasing said switch, and a resistance at the substation for preventing premature operation ot said release mechanism.

VIn a telephone system, a trunk line, an automatic switch, a relay for said switch Aincluded in a bridge across said trunk, an operating magnet and a slow acting relay controlled by said first mentioned relay, and means controlled by said slow acting relay for controlling said first mentioned relay.

33S, ln :i telephone system. an automatic switch, a relay toi' said switch, a magnet for controlling said switch controlled by said relay, and a slow acting relay controlling said first mentioned relay, which slow-acting relay in turn is controlled by said first-mentioned relay.

34. In a telephone system, a line circuit, an automatic switch, means for connecting said switch with said line circu'it. a pair ot' relays in bridge of said linccircuit, a third relay in said bridge. an operating magnet lor said switch controlled by Aone ol" said iirs't mentioned relays, and means controlled br `aid third'relay for preventing the operation olI said magnet.. i

Ifi. lu a telephone system. a trunk line, au automatic sw itch, a relay lor said switch included in a bridge across said trunk, an operating magnet and a slow acting relay controlled by said lirst mentioned relay, means controlled by said slow acting relay for controlling said lirst mentioned relay, and indicating means at the sub-station responsive to the operation of said iitch.

36. In a telephone system, an automatic switch, a relay for said controlling' said switch controlled by said relay, a slow acting relay controlling said iii-st mentioned relay, and indicating means at the sub-station responsive to the operation oi" said switch.

37. In a tclphone system, a line circuit, an automatic switch. means for connecting said switch with said line circuit, a pair of relays in bridge of said line circuit, a third relay in said bridge, an operating magnet for said switch controlled by one of said first mentioned relays, and means at the substation for controlling said third relay to prevent the operation of said magnet.

38. In a telephone system, trunk lines di` vided into groups, an automatic switch having motion in one plane to select a group, and motion in a plane at right angles thereto to lind a line in a selected group, a relay for said switch included in a bridge across said trunk, an operating magnet and a slow acting relay controlled by said first mentioned relay, and means controlled by said slow acting relay for controlling said first mentioned relay.

In a telephone system, trunk lines divided into groups, an automatic switch having motion in one plane to select a group, and motion in a plane at right angles there` to to [ind a line in a selected group, a relay for said switch included in a bridge across said trunk, an operating magnet and a slow acting relay controlled by said first mentioned relay, means controlled by said slow acting relay for controlling said Hrst mentioned relay, and indicating means at the sub-station responsive to the operation of said switch.

40. In a telephone system, lines divided into groups, an automatic switch having motion in one plane to select groups, and motion in a. plane at right angles thereto to find a line in a selected group, a relay for said switch, a magnet for controlling said switch controlled by sail relay, and a slow acting relay also controlled by said first mentioned relay, which in turn is controlled by said slow acting relay.

41. In a telephone system, lines divided into groups, an automaticswitch having n10- tion in one plane to select groups, and Inotion in a plane at right angles thereto to find a line in a selected group, a relay for said switch, a magnet for controlling said switch controlled by said relay, a slow acting relay also controlled by said first mentioned relay, which in turn is controlled by said mgv relay, and indicating means at the subswitch, a magnet for slow act-I station responsive to the operation of said Switch.

42. In a telephone. system, lines divided into groups, an automatic switch having moplane line in a selected group, a line relay and a slow acting relay adapted to control the said vertical motion, and means controlled at the sub-station for preventing this operation. f

44. In a telephone system, subscribers lines. a selector switch having a vertical stepby-step motion adapted to extend connection from a calling subscribers line to a called subscribers line, a line relay in said selector, a magnet for controlling said step by step motion and a slow acting relay connected in multiple circuits and controlled by said line relay, means for energizing said line relay and thereby energizing said vertical magnet and slow acting relay, and means controlled by the slow acting relay for deenergizing said line relay.

1li. In a telephone system, subscribers lines divided into groups, an automatic switch having motion in one plane to select groups and motion in another plane to find a line in a selected group, a pair of relays bridged across said line, a third relay included in said brid e, a side switch controlled by said third relay, an operating magnet controlled by said pair of relays, and means controlled at the sub-station for controlling said third relay to prevent the operation of said operating magnet.

4G. In a telephone system, a subscribers line, an automatic switch having a vertical step by step motion, a line relay and a. slow acting relay forming a reciprocating element to produce impulses for raising the shaft, a magnet at the substation responsive to said impulses, and a resistance at the sub-station adapted to be bridged across the line to prevent the operation of said relays.

47. In a telephone system, subscribers lines, a central office, automatic switches at said central olice` means whereby a called subscriber can signal the central office, means for releasing said switches, and means for preventing the releasing of said switche`y until after the operation of said signal.

at right angles thcre` 4S. In a telephone system, subscribers Y Signed by me at Edmonton, in the Provlines, a central olce, connector switches, ince of Alberta.v` Canada, this 31st day of 10 means for operating the same, a pair of re- May. 1909. lays bridged across the called line, means MER KIRB whereby the subscriber can control said re- O lays to operate a suitable signal, and means itnesses:

for preventing the release of the switches C. E. MACDONALD,

until after the operation of said signal. v A. J. lV. MUSTARD. 

